This is the very first episode of The Master Key. Various stars join the show and reveal their charms. Especially, viewers get to see the hottest idol group members that are rare to see all together at the same time. Baek Hyun of Exo and Jin Young of B1A4 show a different side. Also, Kang Daniel and Ong Seong Wu of Wanna One provide a new image from their group activities. The stars try to find the one who is hiding the Master Key.